Directional gyroscope



Nov. 9, 1943. F. w. MEREDITH 2,334,116

DIRECTIONAL G-YROSCOPE l Filed Nov. 19, 1942 Patented Nov. 9, i943 s PATEN lorries nmEorroNsL Gmosoorn Frederick william Meredith, randen, mund. assigner to S. Smith Sons (Motor Accessories) Limited, Crieklewood. Londo British company nrEnxla-nd. s

- application November is, iste, s'ernigfglo. 466,163

Great Britain A s on. Lroi'. ss-lzcsl This invention relates to directional gyroscopes z of the d provided with an indicator in which relative movement taires piace between an indieating member moving with the gyro and another indicating member attached to the part inwhioh the syro is mounted. As 'is known, gvroscopes are subject to precession due to friction and the earths rotation, and it is therefore necessary to provide means for refsettlng the gyroscope. it

has been proposed to effect re-setting of the erro and its indicator after the gyro has processed, by temporarily casing the syroscope against proces sion and then rotating it to the desired position. Alternatively, the svro has been caused to process to desired position. It has' also been proposed to arrange for the indicating scale on the gyroscope to be detachable and to ee'ct resetting by detac the indicating scale and rotating` it relatively to the gyroscope tothe desired positi where it is re-attsched. 'These prior arrangements are either complicated or are apt to disturb the gyroscope or both. One object of the present invention is to provide resetting means which do not necessitate detaching the indicating member from the gyroscope or disturbing the syroscope.

According to this invention, a directional eyroscope of the hind referred to is characterised in that the i the indicating member driven thereby, and an adjusting member of the resetting Y device, are interconnected by a differential gear,

the normally xed reaction member of which gear is connected with said adjusting member. For example, the indicating member is driven by the movement of the planet carrier of the dierential gear, and the syro and adjusting member are arranged to drive respectively the two crown wheels which engage the planet wheels on said carrier. Y A transmission between the gyro and indicating member may be such that the direction of rotation of the indicating member es viewed bythe operatonis the same as that of the craft when viewed from above.

The indicating member may be arranged to rotate in a plane substantially parallel tothe azimuth axis of the gyroscope.

The indicating member may be ,si

be provided foradjusting the position 'of said scale, while preferably simultaneously adjusting the position of the indicating member for the following` purpose. The scale may be a compass scale. and when the craft is set into anew course,

@d t0 i move over a normally nxed scale, and means may gyroscopic direction-indicating instrument according to this invention. reference being made to the accompanying drawing, inwhich: f

Figure 1 is a vertical section through strument, and

Figure 2 is an elevation of Figure -1.

The Eyroscope is oi the usuai form, in so fer as it has a horizontal spin axis i0, sn inner ring il pivoted about e. horizontal axis i2, an outeror azimuth ring It 4n'iounted to rotate about a verticalaxis and the usualanti-topple devices (not shown) The azimuth ring is mounted on a thrust bearing comprising rollers ifi mounted in a cage i5 between upper and lower races it and i'i. The upper' race it is secured to the azimuth ring so as to rotate therewith, and the bottom race, which the 1n'- iookmg from une left is normally xed, is, however, capableof rotation about the azimuth anis, as hereinaiter described..

.up the rotation of the-case. and is also such-that the pointer, as viewed by the operator, rotates in the same direction as the movement of the aircraft when viewed from above. The pointer is arranged to rotate over a compass scale i@ which is normally xed,but which can be ad- .iusted to rotate about the e airis .as that of the pointer. v

' 1The resetting means comprises a gear drive between a setting member @i and the bottom rece ii, which gear drive is o. worm it and worm wheel 23 of the irreversible hind., the wormwheei 23 being connected to the bottom rece iii and the worm through a shaft t to the setting member 2 i. Thus, when the settins member is not beine operated, the bottom race is locked against movement. The setting member is axially movable in relation to said wo end has a squaresection socket 2b which slidably engages a square-section part 26 of the shaft 26. In one of the axial positions oi the setting member. in addition to engaging the worm shaft. a conical friction surfaced member di on the setting mem- I ber engages e conical'fsce 29 formed on a part it may be that the indicating member is brought to an awkward position for viewing; to overcome 65.

of a pinion 2SI which engages s toothed disc t@ carrying the compass scale 2t. The two friction faces are normally maintained in engagement by a spring 21' compressed between a. shoulder on member 21 and a bracket 28'. The gearing provided by the pinion and toothed disc is such that when the knob is rotated the scale is rotated at the same rate as the pointer, for the purpose above described.

It will therefore be seen that the thrust vbearing forms a differential gear, one member of which (the top race I6) is driven by the azimuth ring I3, the second member of which (the bottom race Il) is driven by the resetting means 2i, 2t, 23, and the third member (the cage I5 for the rollers It) drives the indicating pointer i9. Thus, when the bottom race Il is flxed'relatively to the case of the instrument, rotation of the top race I6 with the azimuth ring I3, will, rotate the pointer I9 to indicate said movement.

If it is required to reset the pointer to a new position, it is only necessary to press inl and rotate the setting member 2i, thus rotating the bottom race I? and so rotating the cage I5. In other words, a dierentialmovement is fed into the connection between the pointer I9 and the azimuth ring I3 without the necessity for disconnecting the pointer from the azimuth ring or in any way disturbing the gyroscope.

A further advantage of the construction dey scribed above is that if after a course has been set on the card in the manner described above, the pointer is not vertical, the resetting member may be rotated in its normal axial position with the friction faces of elements 2l and 29 engaged whereby the pointer and card may be rotated together until the pointer is vertical. The casing 3l of the instrument may be provided with a fixed lubber mark 32 by means of which the setting of the compass scale 20 may 'be read and which also enables a deviation of course to be determined according to the position of the pointer I9 in relation thereto. The .casing is provided with a window 33 marked with parallel lines 3B to emphasise small movements of the pointer I 9. The pointer is also provided in known manner with a small silhouette 35 oi an aeroplane to prevent ambiguity in the interpretation of the sense of a deviation.

The pointer may be extended beyond the periphery of the compass scale so that it can be seen through a second window when in the vertical position against a xed scale with centre zero. It can then be used as a deviation indicator against this scale.

I claim: g

1. A gyroscopic direction-indicating instrument comprising a rotatably adjustable indicating scale, a pointer adapted to rotate around said scale, a gyro, a rotatable setting device movable axially between two positions, an epicyclic difdevice and pointer,

ferential gear interconnecting the gyro, setting device and pointer, and means operable by said settingdevice in one of its positions only for adjusting said rotatably mounted scale as well as said pointer. l 2. A gyroscopic direction-indicating instrument comprising an indicatingscale, an indicating member adapted to move over said scale, a. gyro, a resetting device, an epicyclic differential gear connecting the gyro, indicating member and resetting device together whereby the indicating member may be moved both by the gyro and the resetting device, means affording a. selectively operable connection between said resetting device and said scale for adjusting said scale along with .said indicating member, and means for effecting said last named connection. 3. A gyroscopic direction-indicating instrument comprising a gyro, an indicating scale disposed in a plane substantially parallel to the azimuth axis of the gyro, an indicating member adapted to move over said scale, a resetting device for said member, an epicyclic differential gear comprising a sun element connected with said gyro, a second sun element having an irreversible connection with said resetting device to be driven thereby, and a planet element operatively connected with both of said sun elements,

a planet carrier and means operatively con-v necting said indicating means with said planet carrier, all whereby there is providedfan independent drive between the gyro and said indicating means and between the resetting device and said indicating means.

4. A gyroscopic direction-indicating instrument comprising a rotatably adjustable indicating scale, a pointer adapted to rotatearound said scale, a gyro, a rotatable setting device movable axially between two positions, an epicyclic differential gear interconnecting the gyro, setting and a releasable frictional connection between scale and operable by said setting device in one of its positions for adjusting said rotatably mounted scale as well as said pointer. A

5. A gyroscopic direction-indicating instrument comprising an indicating scale, an indicating member adapted to move over said scale,

a gyro, a resetting device, an epicyclic diierential,

gear connecting the gyro, indicating member and resetting device together whereby the indicating member may be moved both by thegyro and the resetting device, and means affording a selectively operable connection between said resetting device and said scale for adjusting said scale along with said indicating member.

FREDERICK WILPIAM MEREDITH.

said setting means' and saidV 

